This invention relates to a high-voltage transformer, notably for an X-ray apparatus, comprising a high-voltage winding which comprises at least one coil which is supported by an insulating member.
X-ray generators utilize so-called converter generators for generating the necessary high voltage, said converter generators requiring high-voltage transformers operating at frequencies of, for example, 10 kHz. Such transformers require substantially less material and manufacturing effort than 50 Hz transformers. The aim is to achieve as high as possible power densities in order to obtain higher continuous power outputs for a given volume or to reduce the volume for the same power. Therefore, effective steps must be taken for the cooling of the coils. When the operating frequencies are increased, higher losses also occur in the form of copper supplementary losses due to current displacement.
A device of the kind set forth is known from EP-A 84 912 which corresponds to U.S. Pat. No. 4,545,005 Oct. 1, 1985. Therein, wire turns of the coil formers are wound directly in winding chambers of insulating members. Such insulating members are customarily made of moulding resin. Almost the entire coil is enclosed by material having a poor thermal conductivity. Consequently, in the case of high loss power densities, accumulation of heat occurs in the coil and in the insulating member which are thus exposed to a high thermal load.